1. Technical Field
The present invention relates to a buffer circuit and an organic light emitting display with a data integrated circuit using the same and, more particularly, to a buffer circuit and an organic light emitting display with a data integrated circuit using the same, in which a threshold voltage is compensated to supply a correct output voltage.
2. Related Art
Recently, various flat panel displays have been developed, and they substitute for cathode ray tube (CRT) displays because the CRT displays are relatively heavy and bulky. The flat panel display includes a liquid crystal display (LCD), a field emission display (FED), a plasma display panel (PDP), an organic light emitting display (OLED), etc.
Among the flat panel displays, the organic light emitting display can emit light for itself by electron-hole recombination. Such an organic light emitting display has advantages in that response time is relatively fast and power consumption is relatively low. Generally, the organic light emitting display employs a transistor provided in each pixel for supplying current corresponding to a data signal to an organic light emitting diode, thereby allowing the organic light emitting diode to emit light.
The organic light emitting display generates a data signal based on external data, and supplies the data signal to the pixel through a data line, thereby displaying an image having desired brightness. At least one data integrated circuit is employed for converting the external data into the data signal.
The data integrated circuit transforms the external data into a voltage corresponding to gradation, and supplies the voltage as the data signal to the data line via a buffer circuit. Furthermore, in each pixel, current is applied to the organic light emitting diode in correspondence to the voltage of the data signal supplied through the data line, thereby displaying a predetermined image.
In the data integrated circuit, the buffer circuit should ideally transmit the data signal to the data line without a voltage drop. However, the buffer circuit cannot actually transmit the data signal to the data line with a voltage drop as much as the threshold voltage of the transistor because it comprises the plurality of transistors, so that the pixels cannot display an image having the desired brightness.